MONA

Mona is a deployment monitor for ECS services. It will use API periodic calls to know which services are running in the cluster, and what their deployment status is. It will send the following notification:

• A new deployment was started by a user.
• A scaling event happened, i.e. someone changed the desired count of the service.
• A task crashed and the service is recovering.
• A deployment (/scale/recovery) finished.
• A deployment is going on for more than the defined timeout (since latest update). This might also indicates an error.

Deployment

Mona should be deployed as a service (e.g. in ECS) and requires read permissions for ECS.

You can add this policy to the role you use to run the service:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ecs:Describe*",
                "ecs:List*"
            ],
            "Resource": "*"
        }
    ]
}

Configurations

Using mona requires providing a messageSender, a params object and an optional messageFormatter - see below.

the params object

Required params:

• ecsCluster: The cluster to monitor. Currently we don't support multiple clusters.
• AWSRegion: The region the cluster is in.

Optional params:

• serviceNamesOverride: If you want to monitor specific service, provide an array of their names in ECS.
• secondsUntilAlert: Time in seconds to wait for a deployment to finish before sending an alert.
• checkIntervalSeconds: Interval for checking service statuses.
• logInterval: Interval for logging all the service statuses. (number of checkIntervalSeconds cycles).
• refreshServicesInterval: Interval for refreshing the service list. (number of checkIntervalSeconds cycles).

messageSender

Should support the api send: message => {}. See example for slack.

messageFormatter

Provide a message formatter if you want to override the defaults.

You can partially override it by only implementing some functions. The options are

const messageFormatter = {
  deploy: serviceState => '',
  scale: serviceState => '',
  recover: serviceState => '',
  deployDone: serviceState => '',
  deployTimeout: serviceState => '',
  monitorDeploy: (serviceNames, cluster) => '' // sent when mona starts
}

the serviceState includes:

• deploymentId - The primary deploymentId in ECS. Changes every time a user updates the service.
• deploymentCreated - The time of the last update to the primary deployment.
• taskDef - ARN of the task definition in the primary deployment,
• runningCount
• desiredCount

Examples from slack bot

Successful deployment

Recover from error

Scaling event

Deployment timeout